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Update.
It looks like my wireless mouse in the workshop was the problem. I have a computer wireless mouse on my worktop where i build everything, it turns out that this was causing interference to the Uno or the Lm1881, not sure which yet, while it is on i was getting jumpiness on the overlay and it got worse as i moved the mouse.
Just in case anyone else has a problem with sync, it might be worth a look at your wireless kit just to rule it out.
I cannot sync it correctly no matter what i try. Maybe its my TV allthough i have tried 2 tv’s both are modern flat screens. I have tried 2 cameras.
It is a timing issue, i tried a 1M pot from Rset to ground and adjusted it and managed to get the overlay center screen but it was still a little jittery.
I now have 8 spare lm1881’s .. on to the next project.
Just tested it while powered down, i am getting a 1000k reading with the potentiometer all the way over to the right and 1130 k reading with the potentiometer all the way over to the left. This is tested with the 680k resistor in circuit with no Uno board connected.
I have also tested the 680k out of circuit and i am getting a reading of 680k to 679k so i think that resistor is ok.
Just to add, i have done my own PCB for it, the design is more or less identical to yours except i have linked the +5 with tracks not using the whole top copper like your design does. I wanted to use your eagle files but i having problems printing it as the tracks and ground plane are to close together.
Do you think this could be a problem?Hello Michael
The 100k potentiometer is in circuit, and does not seem to affect anything on the overlay.The 680k is a 5% and i think it was measuring about 674k in circuit. I will double check this and exhange it if needed.
I will keep playing the the resistance at the 680k point, As i said in my first post when i check resistance on the 680k while in circuit it centers the overlay and works perfect, (Most of the time). So i think you are right, the problem is going to be that resistor.
I should just buy one of yours, but i allways do it this way. I spend 5 times as much trying to re-produce something and after i fail 5 times i then end up buying a orginal.
Thanks for replying.
